Well, car was in at the dealers for various things (see other about to write post). Got an A4 1.9 TD-red-i (130 I guess) loaner.
First time I've driven one of them. Nice car, loads of pull from low revs. Some pretty serious pull in second gear off roundabouts. Cruised nice, quiet. Overall, well impressed.
Here's the thing though. It's ESP was hyperactive. There's a local roundabout at work and half way round it I floored it and kept it floored as the ESP cut throttle and finally did it's braking thing. All the time though, the car pretty much held the line and kept going. Mucho torque! If I'd done that in the S3, I'd have understeered into the kerb, or worse! Just seemed too easy in the A4.
I asked the tech. about the ESP (re: S3) and he said it's updated often and the most recent revisions in certain cars will allow more "play" than others, including between similar models such as S3/TT. He did actually say that there was critism of it cutting in early and Audi revised it on some models. This *might* explain some of th ESP differences we see on the board, but maybe not.